1. Technical Field
The subject invention relates to the apparatus and method for manufacturing chain pins. More particularly, the subject invention relates to the method and apparatus for upsetting the ends of a solid cylindrical blank to create a chain pin.
2. Description of Related Art
Precision is required when upsetting the ends of solid cylindrical blanks when manufacturing chain pins. The chain pins rotatably interconnect the center links to the side links. Therefore, the smoother the surface of pins, the less wear in the rotational movement of the chain links about or relative to the chain pins. The greater precision in the forming of the pins, the smoother the wear surfaces.
U.S. Pat. No. 2,755,545 to Moore, issued Jul. 24, 1956 discloses an apparatus for forming blanks from ingots of metal. Two hydraulic cylinders on either side of the metal working cavity press the metal into shape of the cavity. This system of pressing metal is not of sufficient precision because two separate hydraulic cylinders are used at either end of the cavity, but are independent and will form non-uniform results if the hydraulic cylinders are not working properly.
U.S. Pat. No. 4,693,107 to Kohama et al., issued Sep. 15, 1987 discloses a method for forming wound bush bearings. The exterior of a bearing is clamped by use of two pairs of tapered surfaces. A mandrel located between the tapered surfaces presses the bush bearing forming a flange after the tapered surfaces have clamped the material in place. This assembly cannot, however, simultaneously work both ends of the bearing because the working force operates in the same direction as the ram, i.e., the direction of movement of the ram and the force are both in the vertically downward direction.
U.S. Pat. No. 3,588,933 to Shinopulos et al. discloses an apparatus for simultaneously upset forming two ends of a blank. This system, however, is silent as to initiating the movement simultaneously.